The wide variety of instant hand sanitizers available to consumers may be grouped into two categories: alcohol-free and alcohol-containing. Of the former category, quaternary ammonium compounds are most frequently employed as the antimicrobial active ingredient. Of the latter category, ethanol at a concentration range of 62-70% w/w is most readily available on the market. In general, both alcohol-free and alcohol-containing products are effective at reducing germs on the skin with a single use. With repeated use, however, alcohol-free products show a significant persistence of antimicrobial activity while alcohol-containing products appear to increase the skin's ability to carry disease-causing pathogens.
An antimicrobial active ingredient that has been used to sanitize hands is chlorhexidine (CHX). In one aspect, chlorhexidine gluconate (CHX-gluconate), a particular salt of chlorhexidine and gluconate, is widely used as a surgical hand scrub and pre-operation skin scrub. The commercially available antiseptic scrub HIBICLENS®, for example, contains 4% CHX-gluconate.
The parent application Ser. No. 14/211,501 and grandparent application Ser. No. 13/529,470 disclose the use of chlorhexidine gluconate in combination with a quaternary ammonium based active ingredient, e.g., benzalkonium chloride. CHX-gluconate is not always desirable in combination with benzalkonium chloride because of regulatory or other issues. It is desirable, however, in certain instances, to use an antimicrobial composition that does not use CHX-gluconate. It has also been found that benzalkonium chloride when used in combination with certain surfactants may damage the skin or cause irritation that is bothersome to the user. The degree of irritation may depend on the surfactant, but it is problematic in certain instances. It is also desirable to use benzalkonium chloride in combination with other ingredients that are chosen to be effective and overcome the drawbacks associated when benzalkonium chloride that is used with surfactants may damage or irritate skin. It is desirable to find a composition using benzalkonium chloride that is formulated with a surfactant and other compounds that mitigate this effect of irritating the user's skin, but maintain effectiveness as an antimicrobial without employing CHX-gluconate.